Effect of volume fraction on magnetoelectric coupling effect of Co0.1Cu0.9Fe2O4/Ba0.8Sr0.2TiO3 composite liquid

Co0.1Cu0.9Fe2O4 (CCFO) and Ba0.8Sr0.2TiO3 (BST) particles were respectively prepared by chemical coprecipitation and hydrothermal method, then CCFO/BST composite liquid was synthesized by distributing surface modified CCFO and Ba0.8Sr0.2TiO3 particles into insulating silicone oil. Effects of volume fraction (ϕv = 1%, 2%, 5% and 10%) on the microstructure, dielectric, ferroelectric and magnetoelectric coupling effect were comparatively investigated. XRD showed that the pure phase of CCFO and BST particles was successfully prepared. CCFO/BST composite particle shows ferromagnetic behavior due to the contribution of magnetic phase CCFO. The dielectric constant of CCFO/BST composite liquid is about 1/25 of the composite particles, and the dielectric constant value of the composite liquid decreases with increasing the volume fraction because the permittivity of silicone oil is far smaller than that of CCFO/BST composite particles. The relative change of dielectric constant of composite liquid under the action of external magnetic field is greater than that of composite particle due to its mobility of particles in liquid. The values of remnant polarization (Pr), coercive field (Ec) and leakage current of CCFO/BST composite liquid increase monotonically with increasing volume fraction, while excessive volume fraction may result in abnormal phenomenon because of the agglomeration of particles. Magnetic field-induced chain structure of the composite liquid has been observed under a light microscope at a magnification of 200. The maximal magnetoelectric (ME) coupling coefficient is about 89.78 V/(cm Oe), which is obtained in the CCFO/BST composite liquid when the volume fraction is 10%.